1. Field of the Invention
The present invention relates to a method for controlling a reactor system. More particularly, the present invention relates to a method for controlling a reactor system comprising a plurality of reactors such as furnaces for thermal decomposition of a hydrocarbon such as naphtha or furnaces for thermal decomposition of a chlorinated hydrocarbon such as 1,2-dichloroethane, for efficient operation of such reactor system.
2. Discussion of Background
In a chemical plant of a type wherein a conversion reaction is conducted by a reactor system comprising a plurality of reactors, it is common to sequentially and periodically stop the operation of the reactors for tuning up, while maintaining the overall size of production of the required product of the entire system at a constant level. Chemical plants of this type include, for example, a plant for thermal decomposition of a hydrocarbon and a plant for thermal decomposition of a chlorinated hydrocarbon. The conventional operation will be described mainly with respect to the plant for thermal decomposition of a hydrocarbon.
A process for producing an olefinic hydrocarbon such as ethylene or propylene by thermal decomposition (steam cracking) of a gaseous hydrocarbon such as ethane, propane or butane, or a liquid hydrocarbon such as naphtha, gas oil, kerosine, light oil or heavy oil, in the presence of steam, is well-known. In such thermal decomposition, formation of carbonaceous substance (coking) takes place in the decomposition tubes of the thermal decomposition furnace, and the carbonaceous substance deposits on the inner walls of the tubes. Therefore, it is common to periodically stop the operation of the decomposition furnace for decoking. An industrial plant for the production of an olefin usually comprises a plurality of decomposition furnaces, e.g. 10 or more furnaces, and it is common to conduct decoking treatment of the respective decomposition furnaces sequentially and periodically, while maintaining the size of production of the olefin of the entire plant at a constant level. In such a case, the operator distributes, based on his experience, the work load corresponding to the size of olefin production of the decomposition furnace under decoking treatment to other furnaces in operation taking into consideration the existing operational conditions of the respective furnaces with due care not to create overloading for the operation of the respective furnaces and accordingly changes the operational conditions (such as the supply of the hydrocarbon starting material or the temperature for thermal decomposition).
However, by such a method wherein the work load for the olefin production is distributed to the respective reactors on the basis of the experience of an operator, the state of deterioration of the respective reactors can not adequately be grasped, and the allowance or tolerance to the operational limits of the respective reactors can not finely and accurately be determined, whereby there have been problems such that an undue load is likely to be exerted to a reactor having no substantial allowance, the cycle for tuning up the reactors, such as decoking of decomposition furnaces, is obliged to be short, and the state of deterioration varies among the reactors.